The present invention relates generally to control apparatus for use in conjunction with conditioned air distribution systems which are employed for heating, cooling and ventilating of buildings and more particularly to an improved variable volume air controller for use in conjunction with such systems.
In heating and cooling of various types of buildings it is common practice to provide one or sometimes more central heating and/or cooling units which operate to deliver a supply of conditioned (either heated or cooled) air to various locations via a duct work system. In one type of system, the heating/cooling unit is operative to continuously provide a supply of air at a substantially constant temperature. In order to control the temperature of the various locations within the building the duct work system is provided with one or more individually controlled variable volume air controllers which operate to vary the volume of the conditioned air which is being delivered therethrough to the various locations. Typically, actuation of the volume air controllers will be controlled by thermostats located within the spaces to which the controller is delivering the conditioned air.
Basically, these variable volume air controllers comprise a housing having an inlet and an outlet connected respectively to supply and delivery portions of a duct work system and a motor driven damper within the housing. The motor drive system will be controlled by a thermostat or other suitable means and operates to position the damper at substantially any setting between and including fully open or fully closed positions so as to modulate the flow of air therethrough.
In order to facilitate modulation of the air flow, the cross sectional area of the volume control housing is typically significantly greater than that of the inlet opening provided therein. Hence, it is desirable to provide means to improve the distribution or diffusion of the air flow entering the housing over the entire cross sectional area so as to enable the damper to more effectively and efficiently modulate the air flow. Further, because the delivery duct work system opens directly into the spaces to be heated or cooled any noise produced as a result of operation of the air controller will most likely be very noticeable and possibly annoying to occupants of those spaces. Accordingly, it is very desirable to design the air controller in such a manner that it will offer substantially noise-free operation both in terms of wind noise which may result from modulation of the air flow as well as vibration of the various components forming a part of the air controller. Additionally, because the duct work system is often located in spaces within the building which are substantially closed off or sealed from the spaces to which the conditioned air is to be supplied, it is desirable that the air controller be substantially sealed so as to prevent leakage of the conditioned air therefrom. Conflicting with this objective, however, is the need to attach various support devices such as hangers and the like to the housing in order to support the air controller which may require puncturing the outer shell thereof.
The present invention, however, provides a substantially improved variable volume air controller which is designed to overcome these problems and provide an extremely quiet and efficient air controller capable of providing substantially noise-free modulation of air flow over substantially the entire range of operation. The variable volume air controller of the present invention comprises an outer shell having a liner fitted therein the sidewalls of which are spaced from the sidewalls of the outer liner so as to prevent penetration of any fastening devices into the interior of the controller and thus reduce resulting air leakage therethrough. Improved air diffusion means is also provided within the controller which operates to distribute the incoming air flow in such a manner as to provide a velocity profile which facilitates efficient relatively noise-free modulation of the air flow over substantially the entire range of operation of the damper. Additionally, stop means are also provided within the air controller which is engageable with the damper so as to prevent movement thereof beyond a full open position. This stop means thus prevents possible misadjustment of drive linkage which could result in the damper being driven beyond a full open position and thus reduce maximum air flow when in fact the control means is signalling for delivery of maximum conditioned air to the spaces. The stop means also includes an air flow deflector which is designed to deflect air flow which would otherwise impinge on the leading edge of the damper when in a full open position thus creating the possibility of noise producing flutter or vibration of the damper. The present invention is also designed to enable inlet plates having different size inlet openings to be easily and conveniently attached to an otherwise completely assembled air controller. Thus, it is possible for a distributor to stock a standard size air controller and to fit an inlet plate thereto having an inlet opening particularly suited for the specific job as opposed to requiring stocking of a variety of different size air controllers. Thus, the present invention provides a variable volume air controller which offers significant advantages over presently available units.